A lot of recent research has pointed to people suffering from addictive personality and not addiction to any particular drug. Some people can actually do heroin once and never again, but it's clearly not the majority.
His son likely had an addictive personality and yes, AAS lead to the Heroin, but not because it's a gateway drug universally, it just was for him.
Addicts will eventually kill themselves, doesn't matter if it's Alcohol, AAS or hard drugs. Nothing will change their fate except for aggressive therapy to change their personality, if this can be done...
End the war on drugs and take a big chunk of the money to convert jails into hospitals. Supply addicts with MJ and provide them with tools to choose the lesser vice. Addict will always be addicts, wether they are addicted to drugs, sex, cleaning house, etc, etc. Teach them to lean towards the lesser harmful vice. Watch your economy explode.